ロテニウムアルキリデン複合体の合成と活性が,フォスフィンとN-ヘテロサイクリックカルベンのリガンドと連携しています
Tina M Trnka1, John P Morgan, Melanie S Sanford
1Arnold and Mabel Beckman Laboratory of Chemical Synthesis, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
Journal of the American Chemical Society
|February 27, 2003
まとめ
この研究では,保護されたN-ヘテロサイクリックカルベン (NHC) リガンドを用いたルテニウム触媒のための新しい,より安全な合成方法が導入され,オレフィン転化反応におけるそれらの有用性を高めています.
科学分野:
- 有機金属化学 有機金属化学
- カタリシス カタリシス カタリシス
背景:
- リンとN-ヘテロサイクリックカルベン (NHC) リガンドを含むルテニウム複合体は,オレフィン代謝において極めて重要です.
- これらの触媒の伝統的な合成は,潜在的に不安定な自由NHCを扱うことを含む.
研究 の 目的:
- ルテニウム-NHC複合体の改良された合成経路を開発する.
- 保護されたNHCアダクトの使い方を検討し,処理を容易にする.
- オレフィンメタテシスで合成された複合体の触媒活性を評価する.
主な方法:
- NHC-アルコールまたは-クロロフォームム添加物を用いてルテニウムアルキリデン複合体の合成.
- ステリカルでボリュームの大きい bis ((NHC) コンプレックス.の準備.
- 結晶構造の決定を含む複合体の特徴化.
- 環閉メタテシス (RCM) と環開メタテシスポリメリゼーション (ROMP) の触媒性能の評価.
主要な成果:
- 保護されたNHCリガンドを用いた新しい,有利な合成経路が確立されました.
- ステリカルにボリュームの高い bis (NHC) ルテニウム複合体は,成功裏に合成されました.
- 混合 bis ((NHC)) デリバティブと C-H アクティベーション製品の結晶構造が決定されました.
- 合成されたNHC-協調ルテニウム複合体は,オレフィン転移活性を示した.
結論:
- 保護されたNHCアダクトは,ルテニウム触媒の合成のために,自由のNHCよりも安全で便利な代替品を提供します.
- 開発された方法は,多様で活性なルテニウム-NHCオレフィンメタテシス触媒の準備を可能にします.
- 副作用と触媒の性能に関するさらなる調査が必要である.
関連する概念動画
Properties of Organometallic Compounds
Organometallic compounds are compounds that contain a carbon–metal bond. Carbon belongs to an organyl group like alkyl, aryl, allyl, or benzyl groups. The metal can be from Group I or Group II of the periodic table, a transition metal, or a semimetal.
Preparation of Aldehydes and Ketones from Nitriles and Carboxylic Acids
Although it is possible to reduce a carboxylic acid to an aldehyde, strong reducing agents, like lithium aluminum hydride (LAH), prohibit a controlled reduction, instead causing the generated aldehyde to instantly over-reduce to a primary alcohol.
Reducing carboxylic acid derivatives like acyl chlorides (RCOCl), esters (RCO2R′), and nitriles (RCN) using milder aluminum hydride agents like lithium tri-tert-butoxyaluminum hydride [LiAlH(O-t-Bu)3] and diisobutylaluminum hydride [DIBAL-H] allows...
Reducing carboxylic acid derivatives like acyl chlorides (RCOCl), esters (RCO2R′), and nitriles (RCN) using milder aluminum hydride agents like lithium tri-tert-butoxyaluminum hydride [LiAlH(O-t-Bu)3] and diisobutylaluminum hydride [DIBAL-H] allows...
Nitriles to Amines: LiAlH4 Reduction
Nitriles are reduced to amines in the presence of strong reducing agents like lithium aluminum hydride through a typical nucleophilic acyl substitution. The reaction requires two equivalents of the reducing agent. The reducing agent acts as a source of hydride ions.
As shown below, the mechanism involves three steps. Firstly, the hydride ion acting as a nucleophile attacks the nitrile carbon to form an anion. In the second step, a second equivalent of the hydride ion attacks the anion to...
As shown below, the mechanism involves three steps. Firstly, the hydride ion acting as a nucleophile attacks the nitrile carbon to form an anion. In the second step, a second equivalent of the hydride ion attacks the anion to...
[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
The Diels–Alder reaction is an example of a thermal pericyclic reaction between a conjugated diene and an alkene or alkyne, commonly referred to as a dienophile. The reaction involves a concerted movement of six π electrons, four from the diene and two from the dienophile, forming an unsaturated six-membered ring. As a result, these reactions are classified as [4+2] cycloadditions.
Diels–Alder Reaction: Characteristics of Dienes
The Diels–Alder reaction brings together a diene and a dienophile to form a six-membered ring. Both components have unique characteristics that influence the rate of the reaction.
Characteristics of the diene
Conformation
The simplest example of a diene is 1,3-butadiene, an acyclic conjugated π system. At room temperature, the molecule exists as a mixture of s-cis and s-trans conformers by virtue of rotation around the carbon–carbon single bond. Although the s-trans isomer is more stable, the...
Characteristics of the diene
Conformation
The simplest example of a diene is 1,3-butadiene, an acyclic conjugated π system. At room temperature, the molecule exists as a mixture of s-cis and s-trans conformers by virtue of rotation around the carbon–carbon single bond. Although the s-trans isomer is more stable, the...
Ziegler–Natta Chain-Growth Polymerization: Overview
Ziegler–Natta polymerization is another form of addition or chain‐growth polymerization used for synthesizing linear polymers over branched polymers. The catalyst used for polymerization is the Ziegler–Natta catalyst, named after Karl Ziegler and Giulio Natta, who developed it in 1953. This catalyst is an organometallic complex of titanium tetrachloride and triethyl aluminum, with the active form of the catalyst being an alkyl titanium compound. Using the Ziegler–Natta catalyst, high molecular...


